To ensure reliability of user data, a storage system generally provides a data copy function, to copy the user data from a source device of the storage system to a backup-end device. When a fault occurs in the source device, the data in the backup-end device is recovered to the source device, thereby achieving an objective of disaster recovery.
In the prior art, generally by using an incremental replication technology, data, which changes, in the source device is compressed and then backed up to the backup-end device. However, in the prior art, copying a data block, which changes, to a backup end still consumes a large amount of bandwidth.